Generally described, a gas turbine includes a number of stages with buckets extending outwardly from a supporting rotor disk. Each bucket includes an airfoil over which the hot combustion gases flow. The airfoil must be cooled to withstand the high temperatures produced by the combustion gases. Insufficient cooling may result in undo stress and oxidation on the airfoil and may lead to fatigue and/or damage. The airfoil thus is generally hollow with one or more internal cooling flow circuits leading to a number of cooling holes and the like. Cooling air is discharged through the cooling holes to provide film cooling to the outer surface of the airfoil. Other hot gas path components may be cooled in a similar fashion.
Although many models and simulations may be run before a given component is put into operation in the field, the exact temperatures to which a component or any area thereof may reach may vary greatly due to turbine hot and cold stretches. Temperature specific properties may be adversely affected by overheating. As a result, many turbine components may be overcooled to compensate for localized hotspots that may develop on the components. Such excess overcooling, however, may have a negative impact on overall gas turbine engine output and efficiency.
There is thus a desire for improved designs for airfoils and other types of hot gas path turbine components. Such improved designs may accommodate localized hotspots with a minimized amount of cooling air. Such improved designs also may promote extended component lifetime without compromising overall gas turbine efficiency and output.